Telescopic sights or scopes are typically mounted to a gun using a pair of mounts attached to the scope and to the receiver or barrel portion of the gun. The mounts may be attached to the gun using screws which thread directly into the gun itself, or using a variety of clamping devices which engage oppositely disposed V-shaped grooves attached to or integrally formed into the gun.
Telescopic sights or scopes have been attached to rifles using a wide variety of mounts. Before telescopic sights became so popular, it was frequently necessary for the gun barrel receiver to be drilled and tapped so that scope mounts could be affixed to the gun with screws. Most modern high-power rifles come predrilled and tapped for scope mount attachment at the factory, with the holes being filled with dummy screws. It has long been a practice with small bore low power rifles, particularly 0.22 caliber rifles, to machine a pair of female grooves on opposite sides of the receiver for attachment of scope mounts. Since 0.22 caliber rifles have very little recoil, axial movement on the scope mounts relative to the gun is not a problem.
It has been a practice of some scope mount manufacturers to attach a plate to the gun defining a pair of dovetail grooves for attachment of the mount. In the late 60's Sturm Ruger and Co. introduced their No. 1 Series, which included a rib attached to the gun having grooves already formed therein for a scope mount attachment. Rather than form the rib for a scope attachment as a separate piece, a number of manufacturers have formed integral dovetail grooves in the receiver of the gun for attachment of scopes. These manufacturers include Sako (Finnish), BSA (British), Mauser (Czechslovakian), and Ruger (U.S.).
In order to prevent axial movement of the mount relative to the gun due to recoil, a number of manufacturers have included lugs or projections on the scope mount which are received in a corresponding recess in the receiver or mount attachment base, as is done with Sako, BSA and Ruger rifles. One of the male dovetails may be formed in the mount and the other adjustable relative thereto as in the case of the Ruger design or both male dovetails attached to the mount may be adjustable as in the case of Sako. Having both male dovetails adjustable allows the scope to be adjusted relative to the gun for windage, an important feature on some of the older European scopes not having internal windage adjustments.
Scope mounts referred to as "See-Thru" have been made for a number of years by J. B. Holden Co. and others. A "See-Thru" mount allows the user of the gun to alternatively use the telescopic sight or conventional open metallic sights. "See-Thru" scope mounts are typically in a figure-8 shape, having a top tubular opening for retention of the scope and a lower tubular opening for free viewing of the iron sight along an axis parallel to the gun bore. It is desirable to have the scope axis as close to the gun bore axis as possible to minimize parallax error. "See-Thru" mounts are typically screwed directly to the gun receiver. In guns which do not employ the "See-Thru" feature, the distance between the scope and bore axis is not nearly as important, as the scope lens diameter typically limits the relative spacing as opposed to mount structure.
A number of scope mounts have been designed so that the scope and mount can be removed and subsequently re-attached to the gun without varying its point of aim or sighting appreciably. These designs typically employ a fixed male dovetail groove which fits into a corresponding female groove attached to or integrally formed in the receiver. A through bolt extends through the mount and supports an adjustable member for cooperation with the opposite female dovetail groove. A separate dependent lug or the transverse through bolt serve to axially align the mount, while the fixed male dovetail serves to laterally align the mount so that it can be removed and re-installed in nearly the identical position. Examples of mounts employing one male dovetail and a movable dovetail adjusted by a transverse through bolt are shown in U.S. Pat. Nos. 3,611,606; 3,424,402 and 3,040,433.
Prior scope mounts of prior art designs typically have one or more of the following problems. They are expensive and made up of many machine parts. They tend to loosen up as a result of recoil and cannot be accurately removed and re-installed in the same place. They tend to be ugly and have numerous sharp edges and projecting parts to snag clothes and brush and, particularly in the case of See-Thru mounts, scopes where are frequently mounted a great distance from the gun bore.